树脂混凝土强度预测的神经网络模型

本文运用均匀设计的方法进行树脂混凝土的配合比设计,用较少的试验取得较好的效果;建立了树脂混凝土的强度预测的神经网络模型,对试验的数据进行了训练和仿真,预测的结果与试验结果吻合非常好。

基于决策树的神经网络预测水泥熟料强度

测定水泥熟料强度的传统方法是实测水泥预制品在第3天与第28天的强度。为了简化并加快熟料强度的预测,设计了基于决策树的神经网络系统。该系统由两部分组成,先利用决策树确定水泥品种,再利用该种水泥样品的数据对神经网络进行训练。实验证明,经过训练的神经网络可以快速、准确地预测熟料的抗压、抗折强度。

大掺量超细粉煤灰对水泥胶砂力学性能的影响

研究了大掺量超细粉煤灰及增强剂对水泥抗压、抗折强度的影响，以及大掺量超细粉煤灰对水泥胶砂凝结时间的影响．试验结果表明：大掺量超细粉煤灰可以提高粉煤灰的最佳掺量范围，大掺量超细粉煤灰大幅度提高了水泥胶砂的强度，尤其是后期强度，同时对早期强度也有明显的改善作用．大掺量超细粉煤灰使水泥胶砂的凝结时间延长．

Effect of waste concrete with different strength on mechanical properties of recycled fine aggregate mortar

The influence of source concrete (SC) with different compression strengths on the workability and mechanical properties of recycled mortar made with river sand substituted by 100% fine recycled concrete aggregates (FRCA) is experimentally investigated. The basic physical performance test shows that with the increase in SC strength, FRCA exhibit lower water absorption and crushing index, meanwhile keeping higher densities. Mechanical property tests, including compressive strength, flexural strength and uniaxial compressive stress-strain tests, show that compressive strength,flexural strength and elasticity modulus of recycled sand mortars increase roughly with the increase in SC strength. The proposed mixture design method demonstrates that all of the components can be kept as the same as those in natural mortar mixture design and FRCA must be pre-wetted before making mortar mixture. Meanwhile, the reuse of higher strength SC can ensure that recycled mortar mixtures are able to achieve similar mechanical performance when compared to natural mortar designs.

Mechanical properties of pervious cement concrete

Compressive and flexural strength,fracture energy,as well as fatigue property of pervious cement concrete with either supplementary cementitious materials (SCMs) or polymer intensified,were analyzed.Test results show that the strength development of SCM-modified pervious concrete (SPC) differs from that of polymer-intensified pervious concrete (PPC),and porosity has little effect on their strength growth.PPC has higher flexural strength and remarkably higher flexural-to-compressive strength ratio than SPC at the same porosity level.Results from fracture test of pervious concrete mixes with porosity around 19.5% show that the fracture energy increases with increasing the dosage of polymer,reflecting the ductile damage features rather than brittleness.PPC displays far longer fatigue life than SPC for any given failure probability and at any stress level.It is proved that two-parameter Weibull probability function describes the flexural fatigue of pervious concrete.

A Study of Compressive, Flexural, Heat Humidity and Heat Transfer of Autoclaved Aerated Concrete Mixed Polypropylene Fiber under Climate of Bangkok

This paper presents the experimental results of study on mechanical properties, heat and humidity transfer through AAC （autoclaved aerated concrete） mixed with PP （polypropylene fiber）. The performance of AAC-PP is investigated in terms of compressive strength, flexural strength, splitting tensile strength, porosity, heat and humidity capacity. The results are compared with control specimen made of autoclaved aerated concrete only （Non-AAC-PP）. Results showed that ultimate compressive strength, flexural strength and splitting tensile strength can be obtained when the content of polypropylene fiber added at 0.75% by volume while porosity of specimens rapidly decreased when content of fiber addition increased above 1% of its volume. Additional, a comparison study of heat and humidity transfer properties on AAC-PP walls showed that the AAC-PP house had lower indoor air and moisture content than （Non-AAC-PP） house. Therefore, addition PP fiber on AAC increased mechanical properties, enhanced hygrothermal performance and reducing moisture content under tropical climate of Bangkok.

Strength Experiment and Mechanism Analysis of Cement Mortar with Sticky Rice Pulp

Cement mortar with sticky rice pulp is an innovative composite material.Investigating its mechanical properties and strength mechanism is essential for the future engineering application.Taking the pulp concentration and the mortar ages as the variables,we tested five groups of blocks for the compressive strength and flexural strength,and observed their microstructures with a scanning electronic microscope.The results indicated that the microstructure got dense if the added pulp had a concentration of about 0.3%,and thereby its flexural strength would significantly improve,while the hydration products agglomerated and the microstructure got loose if the added pulp had a concentration of more than 1.0%,which caused a substantial decline in flexural strength.Besides,the hydration reaction was hindered at the early stage due to the addition of the pulp;hence the early strength of the mortar is on the low side.According to the strength mechanism analysis,all the results are mainly attributed to the effects:"water-reduction",agglomeration and retarding,caused by the addition of the pulp.